Faulty or contaminated cylinder 1 fuel injector preventing a stable pulse offset from being learned; Wiring damage or poor terminal tension at the cylinder 1 injector connector; Engine mechanical issue on cylinder 1, such as low compression or a sticking valve, that skews the learn value; Intake or vacuum leak affecting cylinder 1 airflow and making the offset unlearnable; ECM software calibration issue or corrupted adaptive memory; Low fuel pressure or a restricted fuel supply that prevents the learn routine from completing; Aftermarket or incorrect injector installed on cylinder 1 with different flow characteristics

DTC codes / P2Bxx · Hybrid propulsion / P2B10

P2B10Cylinder 1 Injection Pulse Offset Not Learned

Q: What does code P2B10 mean?

Cylinder 1 Injection Pulse Offset Not Learned. P2B10 means the engine control module (ECM) has not successfully learned the injection pulse offset for cylinder 1, which is the small fuel-delivery correction it applies to that cylinder's injector to keep combustion balanced. The ECM runs a learn routine during specific operating conditions and stores this code when the adaptation value cannot be written or verified within the allowed time or range.

P2B10 means the engine control module (ECM) has not successfully learned the injection pulse offset for cylinder 1, which is the small fuel-delivery correction it applies to that cylinder's injector to keep combustion balanced. The ECM runs a learn routine during specific operating conditions and stores this code when the adaptation value cannot be written or verified within the allowed time or range.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaHybrid propulsion

Symptoms you may notice

Malfunction indicator lamp (MIL) illuminated, often with no other noticeable symptoms
Slight rough idle or uneven engine operation when the fault is active
Momentary hesitation or stumble during light acceleration
Poor fuel economy if the ECM defaults to a rich or unbalanced injection strategy
In rare cases, a pending misfire code for cylinder 1 may accompany the warning light

Common causes, most likely first

Faulty or contaminated cylinder 1 fuel injector preventing a stable pulse offset from being learned
Wiring damage or poor terminal tension at the cylinder 1 injector connector
Engine mechanical issue on cylinder 1, such as low compression or a sticking valve, that skews the learn value
Intake or vacuum leak affecting cylinder 1 airflow and making the offset unlearnable
ECM software calibration issue or corrupted adaptive memory
Low fuel pressure or a restricted fuel supply that prevents the learn routine from completing
Aftermarket or incorrect injector installed on cylinder 1 with different flow characteristics

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm when and under what conditions the learn routine failed
Inspect the cylinder 1 injector connector and harness for corrosion, chafing, or loose terminals
Perform a fuel pressure and injector balance test to compare cylinder 1 delivery against the others
Run a compression test and cylinder leak-down test on cylinder 1 to rule out mechanical causes
Check for intake and vacuum leaks near cylinder 1 using a smoke machine or propane enrichment
Verify the ECM calibration is current and, if required, perform the manufacturer's injector offset relearn procedure
Replace the cylinder 1 injector only after electrical and mechanical checks pass, then clear the code and complete a drive cycle to confirm the learn completes

Why the offset learn fails without a misfire

A P2B10 can set with no driveability complaint because the ECM may substitute a default offset that keeps the engine running acceptably while the learn remains incomplete.
Technicians often replace the cylinder 1 injector first, but a dirty or worn injector is only one cause; a marginal compression reading on that cylinder will also prevent the offset from learning.
The learn routine typically requires a specific coolant temperature window and steady load, so short-trip driving or a thermostat stuck open can block the learn from ever running.
An aftermarket injector with a different spray pattern or flow rate on cylinder 1 will produce an offset outside the learnable range even though the part is new.
Corrupted adaptive memory in the ECM can mimic a hardware fault, so a software update or adaptive memory reset should be attempted before condemning injectors or wiring.

Can I keep driving with P2B10?

The vehicle is generally safe to drive because the ECM falls back to a default injection offset, but prolonged driving with an unlearned offset can cause rough running, higher fuel consumption, and eventual misfire damage. Avoid heavy towing or sustained high-load driving until the fault is repaired and the learn routine completes.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.